Twinning‐Mediated Growth of Al₂O₃ Nanobelts and Their Enhanced Dielectric Responses

Abstract

1-butyl-4-(4¢-pyridyl)-pyridinium bromide with P-V was carried out at a molar feed ratio of two units of 1-butyl-4-(4¢-pyridyl)-pyridinium bromide per vinylbenzyl chloride unit in ethanol. The product after this reaction is denoted as P-V-V.The reaction of P-V or P-V-V nanospheres with gold(III) chloride was carried out by dispersing 0.4 mg mL ±1 of the nanospheres in a standard gold chloride solution of 200 ppm Au (obtained by diluting gold(III) chloride standard solution (1000 ppm Au) in 0.5 M HCl) in Pyrex tubes. The tubes were purged with argon for 30 min and then sealed with rubber stoppers and exposed to UV irradiation in a Riko rotary photochemical reactor (RH400-10W) at 20 C for various periods of time (Step c in Scheme 1).After the reaction of the P-V or P-V-V nanospheres with gold(III) chloride solution, centrifugation was carried out. The supernatant was discarded and the nanospheres were redispersed in doubly distilled water and re-centrifuged for three cycles before being subjected to the following analyses. XPS analysis of the nanospheres after the various functionalization steps was made on an AXIS HSi spectrometer (Kratos Analytical Ltd.) using the monochromatized Al Ka X-ray source (1486.6 eV photons) [30]. UV-vis absorption spectroscopy was carried out using a Shimadzu UV-3101 PC scanning spectrometer, with doubly-distilled water as the reference. Field emission scanning electron microscopy (FESEM) using a JEOL JSM-6700F FESEM was performed at an accelerating voltage of 5 or 15 kV. Transmission electron microscopy (TEM) analysis was carried out on a JEOL 2010 TEM at an accelerating voltage of 200 kV. X-ray diffraction (XRD) analysis of the nanocomposites was performed on a Shimadzu XRD-6000 spectrometer with Cu Ka monochromatic radiation source, at 40 kV and 30 mA. The scanning 2h range was from 10 to 80 with a scan rate of 3 min ±1 .Received The discovery of carbon nanotubes [1] has resulted in extensive investigations to understand the novel physical properties of one-dimensional (1D) nanoscale materials and their potential applications in constructing nanoscale electric and optoelectronic devices.[2] Recently, a new distinct family of onedimensional nanostructures, i.e., nanobelts or nanoribbons, has attracted considerable attention. This morphology, first synthesized by Wang et al., was found to be defect free and proposed as an ideal model for the examination of quantum transport and as building blocks for nanodevices.[3] Subsequently, typical binary oxide nanobelts such as ZnO, SnO 2 , Ga 2 O 3 , CdO, and MoO 3 have been successfully synthesized in several groups. [4] Owing to its special properties, such as high elastic modulus, thermal and chemical stability, high strength and toughness, and excellent dielectric properties, alumina has been regarded as a material of outstanding performance, especially under tension or bending conditions.[5] While recent efforts have been devoted to the synthesis of alumina nanostructures, [6]

Synthesis, photoluminescence and dielectric properties of O-deficient SnO2 nanowires

“…On the other hand, SCP process also contributes to the enhanced dielectric response. It is known that interface density of the nanostructures is much more than that of bulks, and lots of defects such as dislocations, dangling bonds and microporosities exist in the interfaces [13][14][15]30]. Then, the space charges in the nanowires will move towards the opposite poles of the electric when exposed to the external electric field.…”

“…Compared with these optoelectronic properties, the dielectric behaviors of SnO 2 nanowires are poorly known. It is well known that the enhanced dielectric behaviors can be observed in some metal oxide nanostructures such as Al 2 O 3 nanobelts [13], ZnO tetrapods [14], MgO nanoflowers [15] and SnO 2 nanoparticles [16,17] because of a great space charge polarization (SCP) process. As for n-type SnO 2 , O vacancies as native defects can influence the optical and electrical properties of the nanowires.…”

Controllable synthesis of EuCO3OH microspheres and their thermal conversion to Eu2O3

“…Micro-/nanostructured materials with highly specific morphology and novel properties are of great interest to chemists and material scientists [1][2][3][4]. In the past few decades, many synthesis methods have been employed to control the architectures of materials, including template-directed synthesis [5], chemical vapor deposition [6], sol-gel method [7], solution-phase method [8] and so on.…”

Ionic liquid‐assisted hydrothermal synthesis of γ‐Al2O3hierarchical nanostructures

“…is generally difficult and it still remains a great challenge to find a general synthetic scheme for formation of hierarchical nanostructures with well-controlled shape, size, and composition at different levels. Alumina is a well-studied traditional structure material with valuable applications [8] in photoluminescence, dielectric response, and selective catalysis. Doubtlessly, tailored alumina hierarchical nanostructures are promising for the realization of multifunctional nanodevices.…”